3.A.1.153.1ABC transporter complex YtrBCD that may play a role in acetoin utilization during stationary phase and sporulation (Yoshida et al. 2000). Expression is induced early in the stationary phase. The six ytr genes form a single operon, transcribed from a promoter present upstream of ytrA. YtrA, which
possesses a helix-turn-helix motif of the GntR family, may be a
repressor that regulates its own transcription as well as the whole operon. Inactivation of the
operon led to a decrease in the maximal cell yield and less-efficient
sporulation. B. subtilis produces acetoin as
an external carbon storage compound and then reuses it later during
stationary phase and sporulation. Possibly the Ytr porter plays a role (Yoshida et al. 2000). The YtrEF system, believed to be a distinct ABC efflux system (M. Saier, unpublished results), can be found under TC# 3.A.1.122.19.